1. Technical Field
The present invention relates to a liquid ejecting head unit which is used in a liquid ejecting apparatus such as an ink jet type recording apparatus, and a liquid ejecting apparatus and particularly, to a liquid ejecting head unit in which it is possible to detachably mount a plurality of liquid ejecting heads on a head fixing member, and a liquid ejecting apparatus.
2. Related Art
A liquid ejecting apparatus is an apparatus which is provided with a liquid ejecting head capable of ejecting liquid as liquid droplets and ejects various liquids from the liquid ejecting head. As a representative example of the liquid ejecting apparatus, for example, an image recording apparatus such as an ink jet type recording apparatus (printer) which is provided with an ink jet type recording head (hereinafter referred to as a recording head) and ejects ink in the form of a liquid as ink droplets from nozzles of the recording head, thereby performing recording, can be given. Further, in recent years, the liquid ejecting apparatus has been applied to not only the image recording apparatus, but also various manufacturing apparatuses such as a display manufacturing apparatus. Then, in a recording head for the image recording apparatus, ink in the form of a liquid is ejected, and in a color material ejecting head for the display manufacturing apparatus, solutions of the respective color materials of R (Red), G (Green), and B (Blue) are ejected. Further, in an electrode material ejecting head for an electrode forming apparatus, an electrode material in the form of a liquid is ejected, and in a biological organic matter ejecting head for a chip manufacturing apparatus, a solution of biological organic matter is ejected.
In recent years, as the printer, a printer that adopts a configuration (a multi-head type) in which a structure in which a plurality of recording heads having a nozzle row composed of a plurality of nozzles provided in a row are fixed side by side to a head fixing member such as a sub-carriage is set to be a single head unit has been present. Then, in a configuration in which screw fastening is performed in a state where each recording head is positioned with respect to the sub-carriage, after the positioning and before the screw fastening, temporary fixation of the recording head to the sub-carriage by an adhesive (for example, an instant adhesive) is performed. In this way, when main fixation is performed by the screw fastening, the position of the recording head can be prevented from being shifted by rotation moment at the time of the screw fastening. In the case of adopting such temporary fixation by an adhesive, it becomes difficult to detach the recording head once fixed to the sub-carriage in order to repair or replace it. With respect to such a problem, a configuration in which an intermediary member that is called a spacer is interposed between the recording head and the sub-carriage has also been proposed (for example, JP-A-2007-90327). According to this configuration, by fixing the spacer to the recording head in advance by screw fastening, temporarily fixing the spacer and the sub-carriage to each other by an adhesive, and then performing main fixation of the spacer and the sub-carriage by screw fastening, the recording head once fixed to the sub-carriage can be detached from the spacer and the sub-carriage by releasing the screw fastening between the recording head and the spacer. In this way, mounting and detachment of the recording head for repair, replacement, or the like of the recording head is facilitated.
Incidentally, in the structure as described above, in which the recording head is fixed to the sub-carriage with the spacer interposed therebetween, the recording head has flange portions which respectively protrude to both sides with a head main body interposed therebetween, and is fixed to the sub-carriage in a state where the head main body is fixed to the spacers through the respective flange portions. Here, there is a need to maintain a nozzle face of the recording head at a given height position from the sub-carriage with high precision. However, such a height position is made so as to be ensured by the height position from the sub-carriage of the spacer with which the flange portion comes into contact. Therefore, at both end portions of the spacer in a width direction perpendicular to a nozzle row direction of the recording head, reference plane protrusion portions that are convex portions which rise toward the flange portion from a base surface that comes into contact with the sub-carriage are formed, and the surfaces of the reference plane protrusion portions of both the end portions are used as reference planes for the height position. That is, the reference planes are worked with high precision so as to be at given height positions and the height position of a nozzle row with respect to the sub-carriage is positioned with high precision by fixing the recording head to the spacers with the flange portions brought into contact with the reference planes of both the end portions.
However, in an existing spacer, although it has back end-side protrusion portions that are convex portions of the same sort each integrally formed contiguous to the reference plane protrusion portion, convex portions are not present further on the leading end side than the reference plane protrusion portions. As a result, in a case where the spacer is molded using resin, resin sagging caused by the lack of filling of resin due to the residue of gas at the time of molding occurs in leading end portions of the reference plane protrusion portions. As a result, a function as the reference plane of the reference plane protrusion portion is inhibited. That is, a disadvantage such as being incapable of obtaining a sufficient area for coming into contact with the flange portion, thereby stably holding the flange portion at a given height position, arises. On the other hand, in a case where the reference plane of the reference plane protrusion portion is widely formed in advance in expectation of the resin sagging, uniformly working the precision of the height position with high precision is troublesome. That is, since high-precision adjustment of a metal mold is required and the frequency of a periodic maintenance also increases, it leads to an increase in cost. Further, the size of the spacer becomes large, whereby the sizes of the sub-carriage and a carriage become large, so that an increase in the size of the liquid ejecting apparatus becomes large, resulting in a reduction in a commodity value.
In addition, such a problem is similarly present not only in the ink jet type recording apparatus provided with the recording head which ejects ink, but also in another liquid ejecting head unit adopting a configuration in which a liquid ejecting head is fixed to a head fixing member such as the sub-carriage with an intermediary member such as a spacer interposed therebetween, and a liquid ejecting apparatus which is provided with the liquid ejecting head unit.